FGD – Flue Gas Desulphurization
WFGD or seawater-based absorbers
Wet flue gas desulphurization (WFGD)
The most common technology to remove SO2 from a flue gas stream in a coal fired powerplant is the wet flue gas desulphurization (WFGD). Calcium based materials such as limestone, quicklime and calcium hydrate are used in a slurry that serves as absorbens in order to produce gypsum as a by-product of the reaction with SO2.
Depending on the residual liquid content downstream of the mist eliminator, expressed in mg (Liquid)/Nm³ (gas), a two-stage or a three-stage configuration is required.
The configurations consist out of
For vertical flows
- 2 or 3-stage Flat type mist eliminator
- 2 or 3 stage Roof type mist eliminator or
- Combinations out of the 2 types
For horizontal flows
- 2 or 3 stage vane type mist eliminator
The mist eliminators must be operated with a wash system that keeps the mist eliminator clean during operations.
Each type (flat or roof type) has extractable benefits in terms of
- removal efficiency and pressure loss
- cleanability
- construction height
- reduced risk of scaling
- drainability
- flexibility in terms of gas velocity distribution
Ensepatec designs mist eliminator for FGD tower according to the following design criteria:
- Specified residual liquid content [mg/Nm³]
- Maximum pressure loss
- Wash water consumption and slurry pump capacity
- Location of inlet and outlet duct nozzles to identify potential risks from strong flow variations
- Full consideration of absorber geometry
to have a guaranteed result of the separator.
